In PHP, what are the drawbacks of dynamically evaluating expressions using the `eval()` function?

Using the `eval()` function in PHP can pose security risks as it allows for the execution of arbitrary code, making the application vulnerable to code injection attacks. To avoid these risks, it is recommended to avoid using `eval()` whenever possible and find alternative solutions that do not involve dynamically evaluating expressions.

// Example of avoiding eval() function by using alternative solutions

// Instead of using eval() to dynamically evaluate an expression
$expression = "2 + 2";
$result = eval("return $expression;");

// Use a switch statement or if-else conditions to handle different cases
switch ($expression) {
    case "2 + 2":
        $result = 2 + 2;
        break;
    // Add more cases as needed
}